Scanning Electron Microscopy


A Wien filter electron spectrometer has been added to a VG Microscopes, Ltd. HB501 STEM to improve the energy resolution and accuracy of energy loss analysis combined with a high spatial resolution. An energy resolution of 130meV is obtained with a 2mR collection angle at the specimen. The 0.28eV wide field emission energy profile therefore dominates the energy resolution for the device. The energy axis is automatically calibrated by the electrostatic method of scanning, yielding an accuracy and stability of 30meV. A preliminary energy resolution of 0.5eV is demonstrated for 20mR full collection angles at the specimen. Results of experiments suggest that, even with a 0.3eV energy resolution, interband losses below 1.5eV will be hard to observe due to the long exponentially decaying field emission profile. Deconvolution procedures will probably be necessary as a result.

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